Here are the details
The forever paper has been submitted! I began this paper (prematurely, I’ll admit) about 4 years ago. It’s gone through so many versions, I can’t even remember. It is now finally submitted. “This was a triumph. I’m making a note here: HUGE SUCCESS. It’s hard to overstate my satisfaction”. The topic is hard X-rays related to Type III radio bursts. I’ll be keeping my fingers crossed that the reviewer doesn’t give me too much trouble. I’ll post more information later.
by Steven Christe
U.C. Berkeley Ph.D. Dissertation
file [pdf]
The Sun is the most powerful particle accelerator in the solar system, accelerating ions up to tens of GeV and electrons to hundreds of MeV in solar flares and in coronal mass ejections. Solar flares are the most powerful explosions, releasing up to 1032–1033 erg in 102–103 seconds. How the Sun releases this energy and how it rapidly accelerates electrons and ions with high efficiency, and to such high energies, is still not understood. The process of particle acceleration in magnetized plasmas are thought to occur throughout the universe from Earth’s magnetosphere to active galactic nuclei and supernova shocks. The Sun is a unique laboratory for studying these processes. Its proximity allows us to observe it with unparalleled sensitivity and spatial resolution and energetic particles can be sampled directly at Earth after escaping the Sun. The Sun can provide the key to understanding acceleration processes and energy release occurring on cosmic scales. In this thesis, we consider weak hard X-ray (HXR) bursts. In chapter 1, an introduction to the subject of solar observations is presented. Chapter 2 introduces the theory of Coulomb interactions whose understanding is necessary to the quantitative analysis of HXRs. In Chapter 3, the main instrument used in this study is described, the Reuven Ramaty High Energy Spectroscopic Solar Imager (RHESSI). A statistical analysis of the largest sample of RHESSI microflares is presented in Chapter 4. RHESSI microflares are found to be similar to large flares and not important to coronal heating. In Chapter 5, a series of HXR bursts associated with Type III radio bursts are analyzed. It is found that they are a signature of the acceleration process. In Chapter 6, we introduce HXR focusing optics and a new instrument, FOXSI, short for the Focusing Optics X-ray Solar Imager. With its large sensitivity and dynamic range, FOXSI will directly image energetic electron beams as they are accelerated and travel through the corona. FOXSI will be a pathfinder for the next generation of solar HXR observatories.
Though our attention is currently narrowly focused on Super Tuesday, a BBC article caught my attention about a new high speed train called the AVG. Developed by Alstom, the AVG (short for Automotrice à Grande Vitesse) is the successor of the TGV (short for Train à Grande Vitesse). I’m not sure what differentiates a Train from an Automotrice (though it may be the fact the AVG is powered by engines under each carriage rather than being concentrated in the front or rear carriage) but this is pretty cool! France and Japan seem to be the only countries left developing new mass transit technologies which is sad considering the fact that jet powered flight is known to be a major source of pollution (trains on the other hand can run on electricity and have been for a while…cars are playing catch-up). Flying does have many advantages over land transport; it’s fast and there is no need to invest in any infrastructure between the point of departure and arrival, but there is something to be said about the comfort and perceived safety of train travel.
With the new AVG, one of advantages of flying, it’s speed, is reduced. Able to travel at an average speed of 360 km/h (224 mph), the AVG could travel from Paris to Brussels (total land distance of 340 km) in a little under an hour (currently it takes 1:40) while a flight takes approximately 24 min. Of course, due to “heightened” security, the actual traveling time for flying is probably closer to an hour…which is the same as the the travel time of the AVG! Not to mention the fact that airports are usually located far away from city centers while trains can drop you off right in the middle of downtown. This is not to say that trains will ever take the place of passenger jets but I hope that the AVG will force a reconsideration of trains as a viable alternative.
by Hugh Hudson and Lyndsay Fletcher
A new theoretical model for the flare impulsive phase turns everything upside down!
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